• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.4
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• pp.611-621
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• 1995

The objectives of this study are to find out and to analyze the heat transmission characteristics of the conventional and prefabricated Ondol systems. To compare the thermal characteristics of these Ondol, a real sized Ondol model is set in a chamber. Hot water whose temperature is varied from $45^{\circ}C$ to $60^{\circ}C$ with $5^{\circ}C$ interval is supplied to each Ondol system. At that time the temperature distribution of floor surface, the amount of supplied heat, the heat radiation aspect and the heat loss from the floor to the underground are measured and analyzed simultaneously. As a result, even if the supplied hot water temperature to the prefabricated Ondol panel is lower by about $5^{\circ}C$ than that of the conventional Ondol panel, the net radiant effect is same. Heat radiation efficiency of the prefabricated Ondol panel is over 5% better than that of the conventional Ondol panel. It takes 12 hours for the conventional Ondol and 45 minutes for the prefabricated Ondol, respectively to reach steady state.

• Journal of Ocean Engineering and Technology
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• v.21 no.3 s.76
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• pp.1-7
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• 2007

In this study, the heat balance test of an engine was conducted, and the heat released to coolant is measured and corrected using a power adjustment factor for high fuel temperature to simulate heat rejection of the engine. An engine-converter matching simulation program which can compute the engine speed, transmission output speed, transmission input and output power is developed from the vehicle, transmission and engine performance curve. With this information and the engine heat rejection characteristics, the engine and transmission heat rejection rates can be determined at given condition. In analyzing the air mass flow, a sub program computing the air mass flow rate from the equation of the pressure balance between cooling fan static pressure rise and pressure losses of cooling components is developed.

• Journal of the Korean Society of Industry Convergence
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• v.4 no.1
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• pp.35-40
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• 2001

A spectral measurement system for reflection and transmission properties by using an optical fiber and an ellipsoidal mirror was newly developed. The hemispherical reflectance and transmittance spectra of several heating resisting ceramics materials were measured from visible to middle infrared region. The directional characteristics of reflection and transmission were also investigated in consideration of the absorptance. The measured data were analyzed by using a four flux model of radiation transfer, The radiation properties could be estimated by the obtained scattering and absorption coefficient spectra.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.6
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• pp.121-125
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• 2013

This study was carried out to provide a valuable reference which could reduce heating loss of air-inflated double PO film. Therefore, this study was aimed to choose the best air space thickness and injected air temperature. The characteristics of heat transmission variation at experimental materials were measured and analysed in the laboratory. The experiment was conducted of two layers of PO film, each 0.15 mm tick, sandwiching 110, 175, 225 mm of inflated air with 1 m sides. Environmental control lab was constantly controlled with $-10^{\circ}C$ and experiment chamber was constantly changed with 0, 5, 10, $15^{\circ}C$. The analysis of heat transfer showed that heat transmission does not have a direct correlation with Air Space thickness and injected air temperature. But when inside and outside temperature difference of chamber was great, supply of outside air to Air Space had an advantage at reduction of heating load. It was required to examine accurate analysis at a real greenhouse.

• Journal of the Korean institute of surface engineering
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• v.43 no.5
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• pp.211-216
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• 2010

Vacuum carburizing process is well known process for its environment-friendly, low-cost, high-quality characteristics, compared with gas carburizing. In this study, a research was carried out to develop a process of vacuum carburizing for essential components of automotive transmission that is difficult to control its distortion. As a result, vacuum carburizing process is superior to gas carburizing in terms of cost, environment and quality.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.5
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• pp.9-19
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• 1997

In this paper, the modeling and analysis of dynamic characteristics has been carried out for friction clutches and brakes in an automatic transmission. From the operating oil pressure generated by the valve-body, time delay by check valve and the movement of piston has been examined. Also torque capacity and torque transferred at the clutch is studied. Heat capacity and temperature distribution at the reaction plate of clutch are codeled by time-dependent, nonhomogeneous partial differential equation, and brake torque, brake time, and the amount of heat generated are investigated. It is found that the time delay at the check valve is very short but dominant at the spool.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.270-276
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• 2016

This study analysed overall heat transfer coefficient, heat transmission, and rate of indoor air heating provided by water curtain in order to determine the heat transfer characteristic of double-layered greenhouse equipped with a water curtain system. The air temperatures between the inner and outer layers were determined by the water flow rate and inlet water temperature. Higher water flow rate and inlet water temperature resulted in the increased overall heat transfer coefficient between indoor greenhouse air and water curtain. However, it was found that with higher levels of water flow rate and inlet water temperature, indoor overall heat transfer coefficient was converged about $10W{\cdot}m^{-2}{\cdot}^oC^{-1}$. The low correlation of overall heat transfer coefficient between water curtain and air within double layers was likely because the combination of greenhouse shape, wind speed and outdoor air temperature as well as water curtain affected the heat transfer characteristics. As water flow rate and inlet water temperature increased, the heat transferred into the greenhouse by water curtain also tend to rise. However it was demonstrated that the rate of heat transmission from water curtain into greenhouse with water curtain system using underground water was accounted for 22% to 28% for total heat lost by water curtain. The results of this study which quantify heat transfer coefficient and net heat transfer from water curtain may be a good reference for economical design of water curtain system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.674-679
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• 2002

As the object of this study, a transmission system with the style of HST in combination with mechanical semi-automatic transmission for application in hydraulic wheel excavators was chosen. The dynamic characteristics of the object transmission was studied by numerical analysis of the mathematical model. The results of numerical analysis showed comparatively good agreements with experimental results, so the validity of the numerical analysis process was ascertained.

• Journal of the Korean GEO-environmental Society
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• v.22 no.11
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• pp.15-21
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• 2021

Losses of both life and property increased from damage to underground pipe such as heat transmission pipe buried underground in downtown because pipes are gradually aging. Considering the characteristics of the heat transmission pipe, which is not exposed to the outside and difficult to immediately identify problems such as damage, it is realistic to indirectly check the condition of the facility based on the historical information that is periodically collected through facility maintenance. In this study, a methodology for estimating the damage probability was developed by examining the history information of the heat transmission pipe, deriving an evaluation factor that is related to the damage probability. The contribution factor of the damage probability were reviewed by analyzing not only the guidelines for maintenance of heat transmission pipe of advanced European countries and domestic district heating companies, but also the cases of waterworks with similar characteristics. Evaluation factors were selected by considering not only the correlation with the damage probability but also the possibility of securing data. Based on 1999, when the construction technology and standards of heat transmission pipe changed, the damage probability estimation function according to the period of use was divided into the case of being buried before 1998 and the case of being buried after 1999, and presented. In addition, the damage probability was corrected by assigning weights according to the measured data for each evaluation factor such as the diameter, use, and management authority.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.397-402
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• 2001

Due to the recent economic growth and the subsequent increase in demand of electricity, the construction of underground transmission line is also on the rise. Especially, in the metropolitan area, we have much obstruction in laying the line to the central district because of difficulties in procurement of construction land and the increase in the construction cost. Therefore, the necessity of increasing the capacity of transmission line has been suggested. In order to increase the capacity, the electric voltage and current intensity in size-limited lines should be also increased. But, eventually, it leads to the generation of unnecessary heat and the heat radiates through insulation cables and backfill concrete. So we need to develop the material that has good heat radiation characteristics. In this study, we developed and tested backfill concrete that can be a substitute for previously used backfill sand.